Actually, I'm one of those yogurt eating freaks who likes the fruit to be on the bottom, waiting patiently to be stirred in. My reasoning is simple..

It tastes better. I don't know why, or if maybe I'm just loonie, but I'm quite sure that the fruit doesn't taste quite so fruity after it's been stirred in and floating in the yogurt for weeks beforehand. The fruit at the bottom can hold it's fruitiness better when it's lumped together, methinks.

Also, it gives you something to do, makes you feel like you're preparing your yogurt. Ha. :)